In hydraulic cylinders, the working fluid such as hydraulic oil needs to be conveyed to both the extend side and retract side of the cylinder piston in order to make a cylinder rod, which is connected to the cylinder piston, move back and forth. Often, these hydraulic cylinders are used on earth moving, construction, mining and other similar types of equipment. If external plumbing is employed to convey the fluid to either side of the piston, there is a risk that the hose or tubing may be damaged if the plumbing hits an obstacle or the like, damaging the plumbing. This can cause a leak rendering the cylinder ineffective for its intended purpose.
One example of such a cylinder is disclosed in FIG. 1 in U.S. Pat. No. 6,186,043 to Callies. In the '043 patent, hydraulic fittings with metering orifices are provided on top of the cylinder that communicate with radially extending bores that communicate with the extend volume and retract volume on either side of the cylinder piston. Though not shown, tubing, hose or other form of external plumbing is typically used to communicate the fluid to these fittings. As can be imagined, such external plumbing may be prone to damage during use rendering the cylinder ineffective.
Accordingly, a solution that limits the need to use external plumbing to convey the working fluid to either side of the cylinder piston is desirable.